Film-coated wire.



No. 792,001. PATENTED JUNE 13,1905. J.G.CALLAN. FILM 00mm) WIRE.

APPLICATION FILED JULY 25, 1903.

Wibhesses Inventor.

John 6.0a! Ian,

NITED STATES Patented June 13, 1905.

PATENT FFICE.

JOHN G. CALLAN, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

, FILM-COATED WIRE.

SPECIFICATION forming part of Letters Patent No. 792,001, dated June 13, 1905.

Application filed July 25, 1903. Serial No. 166,961.

To all who/1t it 71mg concern.-

Be it known that I, JOHN G. OALLAN, a citizen of the United States, residing at Lynn, in the county of Essex and State of Massachu- 5 setts, have invented certain new and useful Improvements in Film-Coated WVires, of which the following is a specification.

This invention relates to electric conductors; and its object is to provide a metallic conductor with an insulating coating which will add but inappreciably to the bulk of the conductor, will have high insulation, will be inexpensive to apply, and will not deteriorate at ordinary temperatures.

5 The material which forms the main element in my improved coating is collodion. hen applied directly to a metallic wire, this substance produces an unsatisfactory insulation, since it is rapidly destroyed by high temperature, and, moreover, it forms with the superficial oxid of the metal a nitric compound capable of acting on the wire. In my improved conductor-coating the wire is protected from direct contact with the collodion by a prelimi- 2 5 nary layer or layers of some material in the nature of a lacquer or varnish, which completely covers it and excludes the succeeding layers of collodion or other nitrocellulose or mixtures thereof from coming in contact with 3 the metal. A final layer of varnish can also be employed, if desired, to protect the nitrocellulose from the air.

In the accompanying drawings, Figure 1 is a perspective view of a conductor provided with my improved coating, the dimensions being greatly exaggerated for the sake of clearness; and Fig. 2 is across-section of such a conductor, showing a modification.

The conductor 1 is of metal, preferably cop- 4 per, and may be of any desired cross-section and diameter, though the invention is especially applicable to wire only a few mils in thickness. The conductor is first given one or more layers of inert varnish, such as acellulose ester in a suitable solvent, applied either directly upon the wire or secured thereto by a preparatory binder of some adhesive material, such as Canada balsam. I prefer to employ the particular cellulose ester known as 5 cellulose tetracetate, dissolved in chloroform or other solvent, though other cellulose compounds which are waterproof may be employed. The preparation and application of the primary layers are fully set forth in the patent to Thomson and Oallan, reissued May 27, 1902, No. 11,997. As many primary layers of the cellulose ester 2 may be applied as are deemed necessary to effect a complete exclusion of the subsequent layers of collodion from the metal. After this preliminary treat- 6 ment there are superposed on the protectingcoating as many layers as may be required of collodion 3, either plain or mixed with other ingredients, such as camphor. The collodion is first puton by apparatus similar to that set forth in the Thomson and Oallan patent for coating wire with cellulose acetate. A final layer of cellulose ester 4 may be applied to protect the collodion from the atmosphere, though this is not essential.

By using collodion for the body of my insulating-coating I am able to reduce the cost below that of a coating of cellulose acetate alone, while at the same time I obtain an extremely-permanentinsulation within the range of temperature for which it is adaptedviz., up to 65 or 7 0 centigrade.

In accordance with the patent statutes I have described the principle of operation of my invention, together with that which I now consider to represent the best embodiment thereof; but I desire to have it understood that the specific instance given is only illustrative and that the invention can be carried out by other means. 8 5

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. A film-coated wire insulated with collodion and having a protective layer impervious thereto interposed between the collodion and conductor.

2. A metallic conductor having an insulating-coating of collodion, and an interposed protecting-coating of cellulose compound.

3. A metallic conductor having an inner coating of cellulose ester and an outer coating of nitrocellulose.

4. A metallic conductor having an inner coating of cellulose tetracetate and an outer coating of nitrocellulose.

IOO

5. A metallic conductor coated with an inner layer or layers of cellulose acetate and an outer layer or layers of collodion.

6. A metallic conductor coated first with an adhesive binder, then a cellulose ester, and then collodion.

7. A metallic conductor coated with superposed layers of cellulose tetracetate, collodion and cellulose tetracetatc.

8. A metallic conductor coated first with an I adhesive binder, then a cellulose acetate, then collodion, and finally a cellulose acetate.

In witness whereof I have hereunto set my hand this 23d day of July, 1903.

JOHN G. OALLAN.

W'itnesses:

CHATTIN BRADWAY, DUGALD MCK. MoKILLoP. 

